swift234

[swiftc] Add test case for crash triggered in swift::ModuleDecl::lookupPrefixOperator(swift::Identifier, swift::SourceLoc)

Stack trace:

```
6  swift           0x000000000310ab3d llvm::llvm_unreachable_internal(char const*, char const*, unsigned int) + 461
7  swift           0x000000000106f570 swift::ModuleDecl::lookupPrefixOperator(swift::Identifier, swift::SourceLoc) + 0
9  swift           0x0000000000f66048 swift::ArchetypeBuilder::PotentialArchetype::addConformance(swift::ProtocolDecl*, swift::RequirementSource const&, swift::ArchetypeBuilder&) + 296
10 swift           0x0000000000f69a16 swift::ArchetypeBuilder::addConformanceRequirement(swift::ArchetypeBuilder::PotentialArchetype*, swift::ProtocolDecl*, swift::RequirementSource, llvm::SmallPtrSetImpl<swift::ProtocolDecl*>&) + 118
13 swift           0x0000000000f6b9ff swift::ArchetypeBuilder::visitInherited(llvm::ArrayRef<swift::TypeLoc>, llvm::function_ref<bool (swift::Type, swift::SourceLoc)>) + 175
14 swift           0x0000000000f697ea swift::ArchetypeBuilder::addAbstractTypeParamRequirements(swift::AbstractTypeParamDecl*, swift::ArchetypeBuilder::PotentialArchetype*, swift::RequirementSource::Kind, llvm::SmallPtrSetImpl<swift::ProtocolDecl*>&) + 426
15 swift           0x0000000000f69b77 swift::ArchetypeBuilder::addConformanceRequirement(swift::ArchetypeBuilder::PotentialArchetype*, swift::ProtocolDecl*, swift::RequirementSource, llvm::SmallPtrSetImpl<swift::ProtocolDecl*>&) + 471
18 swift           0x0000000000f6b9ff swift::ArchetypeBuilder::visitInherited(llvm::ArrayRef<swift::TypeLoc>, llvm::function_ref<bool (swift::Type, swift::SourceLoc)>) + 175
19 swift           0x0000000000f697ea swift::ArchetypeBuilder::addAbstractTypeParamRequirements(swift::AbstractTypeParamDecl*, swift::ArchetypeBuilder::PotentialArchetype*, swift::RequirementSource::Kind, llvm::SmallPtrSetImpl<swift::ProtocolDecl*>&) + 426
20 swift           0x0000000000f6961c swift::ArchetypeBuilder::addGenericParameterRequirements(swift::GenericTypeParamDecl*) + 172
21 swift           0x0000000000e7d3f7 swift::TypeChecker::checkGenericParamList(swift::ArchetypeBuilder*, swift::GenericParamList*, swift::GenericSignature*, bool, swift::GenericTypeResolver*) + 375
22 swift           0x0000000000e7eb07 swift::TypeChecker::validateGenericSignature(swift::GenericParamList*, swift::DeclContext*, swift::GenericSignature*, std::function<bool (swift::ArchetypeBuilder&)>, bool&) + 135
23 swift           0x0000000000e7eea6 swift::TypeChecker::validateGenericTypeSignature(swift::GenericTypeDecl*) + 102
24 swift           0x0000000000e41f31 swift::TypeChecker::validateDecl(swift::ValueDecl*, bool) + 1601
29 swift           0x0000000000e47556 swift::TypeChecker::typeCheckDecl(swift::Decl*, bool) + 150
30 swift           0x0000000000e6a8e2 swift::performTypeChecking(swift::SourceFile&, swift::TopLevelContext&, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>, unsigned int) + 1026
31 swift           0x0000000000cbcedf swift::CompilerInstance::performSema() + 3087
33 swift           0x000000000078b6ff frontend_main(llvm::ArrayRef<char const*>, char const*, void*) + 2495
34 swift           0x00000000007861c5 main + 2837
Stack dump:
0.	Program arguments: /path/to/swift/bin/swift -frontend -c -primary-file validation-test/compiler_crashers/28266-swift-moduledecl-lookupprefixoperator.swift -target x86_64-unknown-linux-gnu -disable-objc-interop -module-name main -o /tmp/28266-swift-moduledecl-lookupprefixoperator-bacf6e.o
1.	While type-checking 'B' at validation-test/compiler_crashers/28266-swift-moduledecl-lookupprefixoperator.swift:9:1
<unknown>:0: error: unable to execute command: Aborted
<unknown>:0: error: compile command failed due to signal (use -v to see invocation)
```